I want to know the proper way to insulate the walls of my basement and how to determine the proper cold air returns to put in the rooms down there. Presently, the basement in my new home is unfinished with insulation (R8) and vapour barrier down the wall below grade as required.
Answer:
When insulating any below-grade masonry wall it is best to build (in place) a 2X4 structure with studs 16" O.C. and pull it an inch and a half from the wall in order to accommodate R-20 fibre insulation without compressing it. The insulation actually goes from the sub-flooring above to within eight inches of the concrete floor and so does 6mm polyethylene vapour barrier. This system avoids a lot of condensation problems and at the same time, permits a bit of heat loss to the drainage tile along the exterior perimeter of the footings. In areas where frost is a problem, it is important that drainage at this point not be impeded.
